The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.
This invention relates to fire retardants for plastics particularly preceramic additives as fire retardants for plastics and fire retardant blends of such additives and plastics.
Current fire retardants have a number of problems depending on the system. Halogen based fire retardants (which may produce toxic and corrosive combustion products) and phosphorus based fire retardants increase the amount of carbon monoxide and smoke during combustion (by five to ten times), hydrates (e.g. ATH, aluminum trihydrate) which decompose by an endothermic process to produce water, must be used at such high loadings that (40-70% wt) the physical properties of the base polymer are excessively compromised. New fire retardants are needed that do not have these shortcomings. This is especially important for US companies trying to sell products in Europe, where a negative public opinion exists towards halogen base fire retardants, and a new European environmental law, the xe2x80x9ceco-labelingxe2x80x9d law, has passed which requires a label on all products that describes the materials used in the product. These issues are forcing companies to look for new, environmentally acceptable fire retardants for their fire retardant (FR) polymer products.
Accordingly there is need and market for fire retardants for plastics including polymers, which overcome the above prior art shortcomings.
There have now been discovered FR additives for polymers and FR blends of additives and polymers which are effective as such FRs and are environmentally suitable or safe.
Broadly the present invention provides an environmentally friendly (eco) FR for plastics comprising preceramic polymers.
The invention also includes combining such preceramic polymers with plastics as additives and in blends therewith to form eco FR materials.
Such preceramic polymers can be present in the blend in the amount of 1-80 wt% as discussed below.
The invention also provides a method for enhancing the fire resistivity of plastics by adding at least one preceramic polymer to at least one organic plastic to reduce the flammability thereof and form a polymer-plastic blend, wherein the preceramic polymer is selected from the group of polycarbosilanes (PCS), polysilanes (PS), polysilsesquioxane (PSS) resins and polyhedral oligomeric silsesquioxane (POSS) monomers, polymers and copolymers.
Definitions:
By xe2x80x9cpreceramic polymerxe2x80x9d as used herein, is meant an oligomeric or polymeric material that converts into a ceramic (inorganic char,) when heated above its decomposition point. Listed below are several examples of different types of preceramic oligomers and polymers.
By xe2x80x9coligomerxe2x80x9d as used herein, is meant low molecular weight polymer chains that are often unentangled and which do not show the same level of desirable mechanical properties as higher molecular weight chains of the same polymer.
By xe2x80x9cengineering polymerxe2x80x9d as used herein, is meant a thermoset plastic or thermoplastic that maintains its dimensional stability and most of its mechanical properties between xe2x88x9220xc2x0 C. to 200xc2x0 C. Generically these resins include: acetals, polyamides (nylons), polyimides, polyetherimides, polyesters, polycarbonates, polyethers, polysulfides, polysulfones and blends or alloys of them.
By xe2x80x9ccommodity polymerxe2x80x9d as used herein, is meant a thermoplastic or thermoset plastic that maintains most of its mechanical properties between 0 to 100xc2x0 C. Typically such polymers are called commodity plastics because they are also produced on a large scale industrially and hence often cost less per pound than the above mentioned engineering polymers. Examples include: styrenics, acrylics, polyolefins, polyurethanes, polyvinylchlorides and related chlorinated olefins, acrylonitrile-butadiene-styrene (ABS) and poly(ethylene terephthalate).